Stability

(1) Every ship shall be inclined upon its completion and the elements of its stability determined to the satisfaction of IMMARBE. The master shall be supplied with reliable information as is necessary to enable him by rapid and simple processes to obtain accurate guidance as to the stability of the Merchant Ships (Registration) 16 ship under varying conditions of service, and this information shall be forwarded to IMMARBE. (2) Where any alterations are made to a ship, IMMARBE may require additional stability information. (3) The trim and stability data shall include at least the following– (a) full homogeneous load, departure with 100% of all consumables on board; (b) full homogeneous load, arrival with 10% of consumables on board; (c) ballast departure with 100% of consumables on board; (d) ballast arrival with 10% of consumables on board. (4) Where cargo is expected to be carried on weather deck, full load conditions shall be prepared both with and without the deck cargo. Consumables shall include all oil fuel tanks all fresh water tanks, the necessary lube oil, and provision for the crew. The weight of the crew and its effects shall be taken into account in all conditions. (5) The loading conditions shall be in the usual tabular form with small plans of the ship showing distribution of liquids, cargo, etc., and resulting draft, metacentric height (after free surface correction), with stability curves adjacent. (6) The stability characteristics of the vessel in the foregoing conditions shall meet at least the following criteria– (a) the area under the curve of righting levers (GZ CURVE) shall be not less thanMerchant Ships (Registration) 17 (i) 0.075 meter-radians up to an angle 20 when the maximum righting lever (GZ) occurs at 20 and 0.055 meter-radians up to an angle of 30 when the maximum righting lever (GZ) occurs at 30 or above. Where the maximum righting lever (GZ) occurs at angles between 20 and 30 the corresponding requisite area under the righting lever curve shall be determined by linear interpolation; (ii) 0.03 meter-radians, between the angle of heel of 30 and 40 or angle of flooding if this angle is less than 40; (b) the righting lever (GZ) shall be of 0.2m or more at an angle of heel equal to or greater than 30; (c) the maximum righting lever (GZ) shall occur at an angle of heel of 20 or more; (d) the initial metacentric height (GM), after correction for free surface shall be not less than 0.15m. (7) The master shall be provided with approved plans and data as followsOther stability date. (a) the Capacity Plan/Deadweight Scale shall show distribution of all tanks and holds in the ship together with their centres of gravity, longitudinal and vertical, and their free surface inertias. Additionally, either separately or attached to the capacity plan, there shall be a deadweight, tons per cm (or TPI), etc., plotted against a scale of drafts, ranging between the ship’s light and loaded drafts; Merchant Ships (Registration) 18 (b) cross curves of stability shall also be available calculated to include any enclosed structures which may be considered to be realistically buoyant when the ship is heeled to the specific angle; (c) with regard to the curves of particulars, the usual hydrostatic particulars either in curve or tabular form shall also be available for the master, compliance with IMO Resolutions A.167 (ESIV) and A.206 (VII) will generally be regarded as equivalent to the above requirements. (8) At periodical intervals not exceeding five years, a lightweight survey shall be carried out on all passenger ships to verify any changes in lightship displacement and longitudinal centre of gravity in accordance with SOLAS 74, Chapter II- (9) Additional or alternative stability requirements shall be required by IMMARBE for special ships as follows– (a) tugs; (b) supply ships; (c) timber deck cargo ships; (d) heavy lift ships; (e) floating crane; (f) pontoon barges; (g) vessels of novel design. Merchant Ships (Registration) 19